Four credible 787-specific scenarios that could have caused what we saw on AI171:

Recently I came across numerous videos and clips on social media (for ex: YouTube) with 3D simulations regarding the reconstruction of the entire flight path of the ill-fated AI171 crash.

First, let me appreciate all the efforts and the hard work behind putting together such a detailed simulations. It’s very clear that a lot of time is dedicated to the analysis. That said, there is one critical aspect in many videos which is technically off the mark, and I’d like to clarify it. It simply overlooks how fuel cutoff logic actually works in 787 Dreamliner aircraft, which is not just another airliner but a “flying computer", so to say.

On a 787, fuel shutdown does not mandatorily require a pilot physically moving a switch. Multiple logics exist : fault isolation, fail-safe design, bus-powered solenoids, and automatic Fuel Spar Valve (FSOV) closures. which may terminate fuel supply without direct crew input. When any of these trigger, the FDR will still likely record it generically / mimic-record as “Fuel Cutoff.”

In fact, there are totally four credible 787-specific scenarios that could have caused what we saw on AI171:

1) Electrical Cascade / Spurious Command – A major bus failure could have produced a spurious “cutoff” logic, commanding both FSOVs shut.

2) Solenoid Power Loss – If the DC bus powering FSOV solenoids failed, the valves would snap shut in their fail-safe state, instantly starving both engines.

3) Rare FADEC/FMUs Path – Very unlikely, but if FADEC command authority was lost simultaneously, fuel metering could halt. Still, this is far less probable since at takeoff power FADECs are self-sustained via their PMAs.

4) TCMA Intervention – The Thrust Control Malfunction Accommodation system has authority over FADEC in certain edge cases (e.g., overspeed/overboost, unresponsive throttle). A rare but erroneous TCMA-triggered command could theoretically supersede FADEC and shut fuel at the spar, and in the FDR it would still appear as “Fuel Cutoff.”

Few videos have also compared 787 with a car — particularly the “black box” recording ignition vs. fuel starvation. But that analogy breaks down in aviation, especially with the 787, which is not just another airliner but a “flying computer.”, as stated earlier as well. 

The key point: unlike a car, where fuel starvation and ignition state are separate and only driver-action matters, the 787 has automated layers that can mimic a manual cutoff in FDR when, in reality, auto-logic may shut the valves.

RAT deployment in AI171 is fully consistent with downstream loss of both engines due to spar-level cutoff : not necessarily a FADEC-first failure or a manual switch movement in the cockpit.

This is a purely personal, independent unofficial analysis prepared for knowledge-sharing. I will be grateful if experts, engineers, and enthusiasts alike find it worth a read. . together, we can continue striving toward safer skies.